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DISTILLATION   IN   YACl'O                        <S5

second distilling flask, which is tightly attached to the end of
the narrow condenser tube, figured at ti and connected by the
side limb by means of pump-tubing to a water-jet aspirator and

mercury-gauge. Some small bits of porous pot are placed in
the flask, which is heated in a paraffin bath, and the apparatus
exhausted to about 35  40 mm. pressure. At this pressure ethyl
acetoacetate boils at about 90". The following table gives the
temperatures corresponding' to different pressures :-

74-i '
88'

14,

94
97 '

ICK)

- 45
80

The chief inconvenience which attends distillation iwntcito is
the bumping of the liquid in the, distilling ilask. This may be
moderated or removed by various devices, such as the introduc-
tion of porous pot, capillary glass tubes, &c., or by driving a
rapid stream of fine air-bubbles through the liquid. For this
purpose a Claisen flask (Fig'. $7), may be used with advantage.
A tube is drawn out into a fine capillary and is open at both
ends, the wide end being attached to a. short piece of rubber
tubing and screw-clip. This tube is inserted through a cork in